<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      
      .test {
        font-size: 24px;
        color: orange;
      }
      div span {
        color: aqua;
      }
    </style>
  </head>
  <body>
    <button class="test">按钮</button>
    <span class="test">class</span>
    <span>span</span>
    <div>
      <p>
        <span>div的后代span</span>
      </p>
    </div>
  </body>
</html>
